Age-dependent gut microbiota dynamics and their association with male fitness traits in Drosophila melanogaster

Growing evidence suggests that the gut microbiota plays a key role in shaping life history in a wide range of species, including well-studied model organisms like Drosophila melanogaster . Although recent studies have explored the relationship between gut microbiota and female life history, the link between gut microbiota and male life history remains understudied. In this study, we explored the role of gut microbiota in shaping male life history traits by correlating variation in life history traits across genetically homogeneous isolines with their naturally occurring gut microbiota. Using 22 isolines from the Drosophila melanogaster Genetic Reference Panel (DGRP), we measured lifespan, early/late-life reproduction, and early/late-life physiological performance. We characterized the gut microbiota composition in young (5 days old) and old (26 days old) flies using 16S rDNA sequencing. We observed significant variation in male life history traits across isolines, as well as age-related changes in gut microbiota composition. Using machine learning, we showed that gut microbiota composition could predict the age of the organisms with high accuracy. Associations between gut microbiota and life history traits were notable, particularly involving the Acetobacter genus. In early life, the abundance of Acetobacter ascendens was associated with functional aging, while Acetobacter indonesiensis was linked to reproductive senescence. In late life, higher abundances of A. ascendens and Acetobacter pasteurianus were negatively associated with lifespan. These findings highlight the potential role of gut microbiota, especially the Acetobacter genus, in male fitness and aging.